Guard rings are formed in integrated circuits as isolation regions of devices. Conventional guard rings may include semiconductor regions surrounding the circuit devices. The guard rings may be connected to power supply voltages VDD, or may be grounded.
In the integrated circuits that adopt Fin Field-Effect Transistors (FinFETs), the guard rings may also adopt fin shapes. For example, the formation of some guard rings includes etching silicon fins to form recesses, and epitaxially growing silicon germanium in the recesses. The grown silicon germanium forms the guard ring. Since the guard rings are typically long, non-uniformity occurs in the growth of silicon germanium. As a result, some portions of the grown silicon germanium may have thicknesses significantly smaller than other portions. Furthermore, the surfaces of the grown silicon germanium may be rough. This results in a high resistance in the grown silicon germanium and poor landing of contact plugs.